The present invention pertains to the use of the DNA sequence of a Lactobacillus johnsonii strain, in particular to its genomic sequence for elucidating interactions of micro-organism with hosts they colonize, and moreover for elucidating the basis of probiotic properties exhibited by such strain. In addition, the present invention also relates to methods of detecting nucleic acids or polypeptides of Lactobacilli and related species, respectively. A data carrier is provided comprising nucleotide sequences and/or polypeptide sequences of La1.
Lactic acid bacteria, i.e. micro-organisms that produce lactic acid during their (fermentative) activity, are known for a long time and comprise e.g. the genera Lactococcus, Lactobacillus, Streptococcus, Bifidobacterium and Pediococcus. These bacteria are usually prominent in milk and also in milk processing factories, respectively, living or decaying plants and represent a constituent of the intestinal micro-flora in mankind and animals.
Lactic acid bacteria have been utilized as agents for the preservation of food taking benefit of a lowering of the pH and the action of products generated during the fermentative activity thereof to e.g. inhibit the growth of spoilage bacteria. In addition, lactic acid bacteria have also been used for preparing a variety of different foodstuff such as cheese, yoghurt and other fermented dairy products from milk.
Lately, lactic acid bacteria have attracted a great deal of attention in that some strains have been found to exhibit valuable properties to man and animals upon ingestion. In particular, specific strains of the genus Lactobacillus and Bifidobacterium have been found to pass the gastro-intestinal tract in a viable and live form without getting destroyed in the upper part thereof, especially by the impact of the low pH prevailing in the stomach. Moreover, they were found to be able to colonize the intestinal mucosa, with their temporary or sustained presence in the gut being postulated to bring about numerous positive effects on the health of the living beings. These strains are generically termed probiotics.
EP 0 768 375 discloses such a specific strain of the genus Bifidobacterium, that is capable to become implanted in the intestinal flora. This Bifidobacterium strain is reported to assist in immuno-modulation, being capable to competitively exclude adhesion of pathogenic bacteria to intestinal cells, thus supporting the maintenance of the individual's health.
Apart from Bifidobacteria, also some strains of Lactobacilli have been found to exert favorable properties to humans, such as preventing colonization of the gut by pathogenic bacteria or obstructing rotaviral infection. In particular, PCT/EP02/00958 discloses such a strain having both of said properties.
In the last few years the food industry has applied such strains in products, such as milk drinks or fermented acidified milk products. Clinical studies performed with these products and/or the bacterial strains confirmed the notion that these kind of bacteria account for health promoting traits in vivo and may even be utilized for contending diseases, such as ulcers. In particular, a strain of the genus Lactobacillus johnsonii has proven to be capable to combat Helicobacter, an acknowledged cause of ulcer in man.
In view of these valuable properties particular strains of lactic acid bacteria may provide, there is a strong desire in the art for elucidating the molecular basics of these health promoting properties. In particular it would be of great interest to determine the substance or substances responsible for these effect(s). To this end, tools are required to study these micro-organisms in more detail, so as to clarify the molecular principles underlying the probiotic properties, such as interaction with the hosts, the phenomena of passing (survive in) different environmental conditions in the gut as well as having the capability to adhere to the intestine's mucosa and eventually the involvement in the enhancement of the immune system and defense against pathogens, which information will allow a better understanding of these mechanisms.
Consequently, there is a need for the provision of substantial data about bacterial strains that exhibit properties beneficial for man and/or animals. This is now provided by the present invention.